what happens when alum is added to plaster of paris??
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If you need to make a plaster figure, such as a figure for a parade float, you can use cloth dipped in fabric to wrap around your armature. This makes a figure that looks sort of like paper mache but it dries very hard. You can use any type of thin fabric as a dipping cloth such as old sheets, gauze, or shirts or any cheap cotton that you can buy by the yard, such as muslin. You can also use paper towels for smaller projects.
Start by making your armature. An armature is simply the frame you will wrap the cloth on. For small figures you can use balloons, cardboard, styrofoam or boxes. For large figures you can use chicken wire. Once your armature is ready, you can start covering it with dipping cloth!
If you are making a small figure or object, you can use a quick dry plaster of Paris dipping cloth mixture. This mixture dries in about 20 minutes. Simply mix 3 cups of plaster of Paris with 2 teaspoons of powdered alum (look in the spice aisle at the grocery store for alum). Pour 3 cups of water into a separate container (a small bucket works well) and slowly add the plaster of Paris and alum mix to the water while stirring. Stir until is it smooth and creamy.
Take fabric strips and dip them into the cloth. Then wipe the fabric strips a bit so they are not dripping wet and place the cloth strips over the armature. You can add two or three layers of fabric. Remember that you have to work quickly because you only have about 20 minutes before the mixture starts to dry. It will dry very hard.
If you are making a large object such as a parade float figure, you will need a slow drying dipping cloth mixture so you have time to complete your project before it starts to dry. To make a slow drying dipping cloth mixture start by pouring 3 cups of water into a bucket. Then in a separate container mix 2 cups of spackle compound, 2 cups of plaster of Paris, and 2 teaspoons of powdered alum.
hope it helps
Start by making your armature. An armature is simply the frame you will wrap the cloth on. For small figures you can use balloons, cardboard, styrofoam or boxes. For large figures you can use chicken wire. Once your armature is ready, you can start covering it with dipping cloth!
If you are making a small figure or object, you can use a quick dry plaster of Paris dipping cloth mixture. This mixture dries in about 20 minutes. Simply mix 3 cups of plaster of Paris with 2 teaspoons of powdered alum (look in the spice aisle at the grocery store for alum). Pour 3 cups of water into a separate container (a small bucket works well) and slowly add the plaster of Paris and alum mix to the water while stirring. Stir until is it smooth and creamy.
Take fabric strips and dip them into the cloth. Then wipe the fabric strips a bit so they are not dripping wet and place the cloth strips over the armature. You can add two or three layers of fabric. Remember that you have to work quickly because you only have about 20 minutes before the mixture starts to dry. It will dry very hard.
If you are making a large object such as a parade float figure, you will need a slow drying dipping cloth mixture so you have time to complete your project before it starts to dry. To make a slow drying dipping cloth mixture start by pouring 3 cups of water into a bucket. Then in a separate container mix 2 cups of spackle compound, 2 cups of plaster of Paris, and 2 teaspoons of powdered alum.
hope it helps
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Addition of alum to plaster of paris will form keene cement.
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